<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Sugar</title>
</head>

<body>
  <script>
    // 模拟购物车列表数据
    const cartList = [
      { goods_id: 11, goods_name: '商品1' },
      { goods_id: 33, goods_name: '商品3' },
      { goods_id: 22, goods_name: '商品2' },
      { goods_id: 44, goods_name: '商品4' },
      { goods_id: 66, goods_name: '商品5' },
    ]

    const goods_id = 22;
    // findIndex()   查找索引
    //    查找成功：返回数组索引（找到后会自动停止查找）。
    //    查找失败：返回 -1

    // find()        查找数组项
    //    查找成功：返回数组项
    //    查找失败：返回 undefined
    const index = cartList.findIndex((item) => item.goods_id === goods_id);
    const obj = cartList.find((item) => item.goods_id === goods_id);

    console.log('cartList', cartList);
    console.log(`goods_id为${goods_id}的索引值是：${index}`);
    console.log('find查找数组项', obj);

    // const goods_id = 22;
    // let index = 0;
    // for (let i = 0; i < cartList.length; i++) {
    //   const item = cartList[i]
    //   if (item.goods_id === goods_id) {
    //     index = i;
    //     break;
    //   }
    // }
    // console.log(index);

  </script>
</body>

</html>